Photographic developers containing tetrazolyl disulfides as antifogging agents



Patented Nov. 2, 1948 PHOTOGRAPHIC TETRAZOLYL DISULFIDES AS ANTIFOG- GING AGENTS Fritz Dersch and Robert H. Clark, Binghamton, N. Y., assignors to General Aniline & Film Cor poration, New York, N. Y., a corporation of Delaware i No Drawing.

This invention relates to photographic developers containing anti-fogging agents; and more particularly to the use of tetrazolyl disulfides as such agents in developers.

It is known in the art that lightsensitive emulsions, such as gelatin silver-halide emulsions, have a decided tendenc tofog. The fog may be of two types, namely, yellow .fog and chemical (gray) fog. The yellow fog, sometimes referred to as color fog or :dichroic fog, is essentially a colloidal deposit of. silver, the color intensity and general appearance of which are determined by the minute particle size and degree of subdivision. The fog is chiefiyyellow: in color and is most apparent in the lighter portions of a negative. The color may vary, however, and the colloidal silver particles may, for example, appear green by reflected light and yellow or red by transmitted light.- The so-called chemical fog, or gray fog, on the other hand, is the more common and is formed in a number of ways. It may be caused by premature exposure, by eXceSsiVe ripening of theemulsions, or by the storage of the film, particularly at high temperatures or for unusually longperiods of time. i

When photographic plates and films coated with gelatin silver-halide emulsions are allowed toage for periods of time prior to processing, a chemical fog thereafter appears in the unexposed areas upon development. This fog occurs to a somewhat lesser extent when the plate or filmis exposed and developed immediately after coating, providing the plate or film is givena normal period of development; It occurs to a much greater extent if the period of development be unusually long.

It is also known that mercapto tetrazoles and tetrazoles containing atleast one :NI-I group, the hydrogen atom of which is capable of substitution by silver, are effective in preventing an increase in fog and.arethus efiectiye in stabilizing or corn trolling the. keeping. quality of light sensitive silver-halide emulsions. Although these com pounds have the ability 'togive the emulsions to which they are added stability and a steeper gradation, they have a definite shortcoming in that they, to some. extent, lower the sensitivity of the emulsions.

The primary object of the present invention is to provide stabilizers or fog inhibiting agents which are incorporated in the developing bath or inaseparate processing-bath. i q 1 A further objectis to provide stabilizersor fog: inhibiting agents which are incorporatedinto' a black and white or color developerandwhich tendt Application November 7, 1916, Serial No. 708,474

e 16 Claims. (o1.9s-ss) to prevent the formation of chemical fog in lightsensitive silver-halide emulsions without lowering the sensitivity of such emulsions.= w A still further object is to reduce the amount of chemical fog produced upon development of a' silver-halide emulsion by developing'said emul sion with a developer containingafog-inhibiting amount of tetrazolyl disulfide: 1 l

Other objects and advantages willappearlfrom the following specification. .2 l :':w

We have foundthat by combining, in a single compound, both the tetrazole. and disulfide radi cal in the form of a tetrazolyl disuliide, components are obtained which arefar superior in fog reducing action to either radical when used in conjunction with some other group. Such com? pounds may be termed bis(1-substituted-tetra zolyl-5-)disulfides and have the following structural formula? i l i whereR is a hydrocarbon radical, e. g., methyl; ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert.-butyl, amyl, hexyl, heptyl, octyl, nonyl, ally],

phenyl, o-, m-, and p-tolyl, naphthyLa-naphthyl, B-naphthyl, diphenyl, benzyl, methyl benzyl, ethyl benzyl, and the like. l

There are two general methods by whichthe tetrazolyl disulfides may be prepared. The first methodapplies to those tetrazolyls where R in the abovegeneral formula is aliphatic, and the second method to those where R is aromatic. The first method is described by R. Stollin the Journ. fiir prakt. Chemie, 133, p. 60, 1932, and consists of adding fdropwise a solution of any aliphatic isothiocyanate in alcohol to a hot, well-stirred, alcoholic suspension of sodium azide and heating the mixture under reflux for a period of time ranging from 2 to 8 hours. The reaction involved proceeds as follows: I L

NaNz+R1 NC S l i v i v O-SNa wherein R and above. l i l During the reflux, period, astrong stream of CO2. is passed through the well-stirred. reaction R1 are of the same value as R mixture. At the end of the reflux period, the

propargyl, butenyl, pentenyl, hexenyl,

radical, are dissolved in alcohol, such as methyl, ethyl, propyl, and the like, or in a Water mixture thereof, and the solutions thus obtained mixed with any black and white or color developer of the type used in the art in processing black and white and: colonfilm. t X

' Where, however, the 1-position of the tetrazolyl "disulfide is substituted by an aryl radical, such compoundis best dissolved in a small quantity of acetone or dioxane, and the solutions thus obtained mixed with any one of the common black and white and color developers. The concentrationof the fog inhibiting agent employed in either black and white or color developers may vary from about /2 to 500 mgs. per liter of developer or higher.

In order that those skilled in the art may better understand the nature andscope of this invention, the following specific examples are given without any intention of limiting the invention thereto. i

Example IV Example A color developer for forming colored images by coupler development was made up as follows:

p-Aminodiethylaniline hydrochloride grams 2.5 Sodium sulfite (anhydrous) 'do 1.0 Sodium carbonate .(monohydrate) do 67.5 Potassium bromide do 2.0 Water to make; liter 1 Bis (1-phenyltetrazolyl-5-) disulfide Acetone cc. 20.0

For use solution B was added to solution A with rapid stirring.

A subtractive color positive film containing coupling agents in the emulsion layers, such as prepared according to United States Patents 2,179,228, 2,186,849, and 2,220,187, was exposed and developed in the color developer as above described.

It is to be noted that in cases where the emulsion layers do not contain coupling agents, the coupling agents are added to the color developer containing the fog inhibittor and the exposed silver-halide layers processed in the usual manner.

Example VI Example IV was repeated with the exception that an equivalent quantity of bis(1-allyltetrazolyl 5 -)disulfide was substituted for bis(1- methyltetrazolyl-5-) disulfide.

5 Special advantages are gained, when films or plates, which have been stored at high temperatures or for unusually long periods of time, are

developed in a developer, or washed or fixed in a bath containing our fog inhibitors.

Various modifications of this invention will occur to persons skilled in the art and it is, therefore, understood that the patent granted shall only be limited by the following claims.

We claim: i f j 1. A photographic developer containing a developing agent and a fog inhibiting amount of a tetrazolyl disulfide having the general formula:

where R represents a, hydrocarbon radical.

2.A photographic developer containing a developingagent and a fog inhibitinguamount ,of a tetrazolyl disulfide having the formula;

(3H3 CH3 4. A photographic developercontaining a de-,

veloping agent and a fog inhibiting amount of a tetrazolyl disulfide having the formula:

5. A color-forming photographic developer comprising a primaryaromatic amino developing agent and a fog inhibiting amount of a tetrazolyl disulfide having the general formula:

where R represents a hydrocarbon radical.

6. A color-forming photographic developer comprising a primary aromatic amino developing agent and a fog inhibiting amount of atetrazolyl disulfide having the formula:

7. A color-forming photographic developer comprising a primary aromaticamino developing agent and a fog inhibiting amount of a tetrazolyl disulfide having the formula:

8. A color-forming photographic developer comprising a primary aromatic amino developing 1 8 agent and a fog inhibiting amount of a tetraZ olyl disulfide having .the formula: 1 l

Y t t NN N-N N-N N-N S K where R represents a hydrocarbonfradical, N N the presence of a coupler compound. 1 9. The method of preventing the formation of '14. The method of preventing the formation fog upon development of an exposed silver-halide m of "fog u on color development of an exposed emulsion which comprises developing said emulsilver-halide emulsion "containing color-formers sion with a developing agent containing, in a which cor'nprises developing said emulsion with; fog/inhibiting amount,a tetrazolyl disulfide hava developer containing "a Ipri'm'ary aromatic ing the general formula: amino developing agent and, in a fog inhibiting R R amount, a tetrazol'yl'di'sulfidehavingtheformula: l ILI I. -N a (IJHa (1H3 V 1 Hlnd 1 M i N-N N-N NN N-N wherejR represents a hydrocarbon radical. 2O l 11)."The method of preventing the formation g g ii i f fi fi g" of fog upon development of an exposed silve f f. e me 1) od p l t f e a 1 d halide emulsion which comprises developing said 0g ugon 0 f P Q emulsion with a developing agent containing, t h .emulslon cqntalmyrlg 9 T' m? in a fog inhibitingarnount, a tetrazolyl disulfide which comprises Yi 5 Femulswtl t having the formula: a developer conta ning a primary aromatic amino developing agent and, in a fog inhibiting E amount, a tetrazolyl disulfide having the "for- N-N N-N mula:

oss-o N N-N 1'1. The method of preventing the formation of fog upon development of an exposed silverm halide emulsion'which comprises developing said emulsion with a developing agent containing, ll in a fog inhibiting amount, a'tetrazolyl disulfide N havmg the formula: in the presence of a coupler compound.

it l6.Th'e method 'of preventing the formation of fog upon color development of a'n' exposed silver-ha1ide emulsion containing c'ol'or iorm'e'rs which comprises developing said emulsion with a developer containing ;a primary aromatic .45 amino developing agent and, in a reg inhibitin H X' m u e ei ivl d lfi e vin t e o NN N-N mulal 12. The method of preventing the formation E 6 7 of fog upon development of an exposed silver- -l halide emulsion which comprises developing said o's-so emulsion with a developing agent containing, in a -tog inhibiting amount, a tetrazolyl disulfide l having the formula: 1 in the presence of a coupler compound. C H H FRITZ DERscrL. 5 5 ROBERT H. CLARK. N-N NN REFERENCES CITED The iollowing references are'of 'record'inf'the 13 Th th d f V th f t file of this patent: i I i e me o o preven ing e orma lOIl. of fog upon color development of an exposed UNITED STATES PATENTS silver-halide emulsion containing color-formers Number Name Date Which comprises developing said emulsion with 1,962,123 Brooker June 12,1934 a developer containing a primary'aromatic amino 2,1241%?!) Weyde Jul-y 19, 19738 developing agent and, in a fog inhibiting "2,340,763 McQueen c c Feb.1,:11944 amount, a tetrazolyl disulfide having the gen- 2,385,762 Mueller Sept/2511945 eral formula: "2, l03;927 Kendall 'J1i-ly"I6, 1946 g g [tr n r i l l m 

